High-Voltage Capacitor Dielectric for Low TCC Voltage Sensing
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Solution Overview
Problem
Conventional high voltage capacitors experience significant changes in capacitance with temperature, making them unsuitable for applications requiring stability across varying temperature ranges, particularly in high voltage electrical distribution networks where precise voltage sensing is necessary.
Innovation Solution
A high voltage capacitor design featuring a dielectric material composed of first and second dielectric fillers in an insulating polymer matrix, which maintains a capacitance variation of no more than ±0.5% within the 30° C to 60° C temperature range, ensuring a low temperature coefficient of capacitance (TCC) and high voltage withstand, suitable for use in medium and high voltage electrical distribution networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high permittivity dielectric filler materials are added at relatively high loadings to increase capacitance density, then the capacitance density is improved, but the stability of capacitance with temperature deteriorates
Solution Approach 1:
The patent employs a composite dielectric material comprising multiple filler materials (such as barium titanate, strontium titanate, and silica) combined in specific proportions within a polymer matrix. This composite approach allows the material to achieve high capacitance density while maintaining temperature stability, as different fillers compensate for each other's temperature-dependent properties. The synergistic interaction between fillers enables both high permittivity and low TCC characteristics to coexist.
Solution Approach 2:
The patent systematically varies the composition ratios, particle sizes, and loading amounts of different dielectric fillers to optimize the balance between capacitance density and temperature stability. By adjusting parameters such as the ratio of high-permittivity to low-permittivity fillers, and controlling the distribution of particle sizes, the material achieves a capacitance density of at least 5 nF/mm³ while maintaining a TCC of ±125 ppm or less.
2Ease of manufacture
If conventional dielectric materials are used in high voltage capacitors, then the manufacturing is simpler, but the change in capacitance with temperature exceeds ±0.5% over the use temperature range
Solution Approach 1:
The patent modifies the dielectric material composition by incorporating specific ratios of high-permittivity fillers (e.g., barium titanate at 20-40 wt%, strontium titanate at 10-30 wt%) combined with silica and other stabilizing materials. These compositional parameter changes enable the material to achieve ±0.5% capacitance stability over the temperature range of -40°C to +85°C, meeting the precision requirement while remaining manufacturable through conventional mixing and curing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a stable capacitance over a wide temperature range, ensuring accurate voltage sensing and reliable operation in high voltage applications, with a TCC of ±125 ppm or less, and a withstand voltage of at least 50 kV, enhancing the reliability and precision of voltage measurement in electrical distribution networks.
Implementation Method 1
a dielectric material disposed between the high voltage and measurement electrodes, wherein the dielectric material comprises first and second dielectric fillers disposed in an insulating polymer matrix
Implementation Method 2
the change in capacitance of the dielectric does not vary by more than +/−0.5% in the temperature range of 30° C. to 60° C., wherein the high voltage capacitor for use with a line voltage of greater than 6 kV, 12 kV or 18 kV
Data Source
AI summary
A high voltage capacitor for a voltage divider is described that is configured to sense an elevated voltage for medium and high voltage electrical distribution networks. The high voltage capacitor comprises a high voltage electrode, a measurement electrode, and an dielectric material disposed between the high voltage and measurement electrodes, wherein the dielectric material comprises first and second dielectric fillers disposed in an insulating polymer matrix such that the change in capacitance of the dielectric does not vary by more than +/−0.5% in the temperature range of −30° C. to 60° C. and the high voltage capacitor has a withstand voltage of at least 50 kV.